On Jan. 4, 1642, King Charles I entered the House of Commons to arrest five members of Parliament for high treason (luckily they had already fled the building).

When he demanded of the Speaker, William Lenthall, where they were, he received the defiant reply, “May it please your Majesty, I have neither eyes to see nor tongue to speak in this place but as this house is pleased to direct me whose servant I am here.”

Fast-forward 377 years (plus five days), and the present Speaker, John Bercow, has ignited controversy, standing accused of trying to be master of the House rather than its servant.

By forcing through a controversial amendment on Wednesday he has spurned the will of the government, possibly altered the course of Brexit by placing more power in the hands of those who wish the U.K. to remain in Europe, and made Prime Minister Theresa May’s position more precarious.

The 55-year-old Conservative MP has been a polarizing figure since becoming Speaker 10 years ago. He has faced numerous allegations of bullying and a damning report last year by a former judge found a culture of bullying at the Commons, especially against women.

Initially on the far right of politics, he later moved to the centre and embraced many of the views of New Labour. Although elected in a secret ballot, it is widely believed he secured the Speaker’s chair only through the backing of Labour MPs. He has often angered Tory MPs — one, Simon Burns, labelled him a “stupid, sanctimonious dwarf” — and William Hague, when leader of the House, tried to get him removed from office.

But he is most likely to be remembered for his decision on Wednesday.

“Bercow’s unprecedented ruling could change the course of Brexit,” said the BBC.

The unprecedented decision was to allow an amendment to a government business motion concerning Brexit. History and precedent did not allow for amendments to such a motion, was the government’s firm view. The same position was held by senior advisers to the Speaker who told him so.

I have never known any occasion when any Speaker has overruled a motion of the House of Commons

But Bercow, who is in the Remain camp over Brexit, was keen to allow the amendment that was widely supported by Labour and some Tory MPs because it would put more pressure on May. The amendment, by a pro-European Tory, would require May to return to Parliament within three days — rather than 21 — to debate the implications of not having a Brexit deal, if the prime minister’s proposals are voted down next Tuesday.

“Bercow was told twice by the clerks that the amendment should not be accepted. However a source said he was ‘livid’ and refused to accept their advice, referring to them as a ‘gaggle’.” reported the Telegraph.

Despite a furious row with the Tory chief whip before Parliament sat on Wednesday, Bercow allowed the amendment to go forward as cries of “pathetic” and “ridiculous” echoed in the chamber.

A government source told the Telegraph, “This just goes to show the extent to which the Speaker will do all he can to prevent the referendum result being implemented. He will end up damaging democracy.”

When Bercow was challenged in the House he refused to reveal what advice he was given and said he was not bound by precedent.

“It is the long-established practice of this House that the Speaker in the chair makes judgments on the selection of amendments, and those judgments are not questioned by members of the House,” he said. “I am clear in my mind that I have taken the right course.”

In an hour-long heated debate, he was also accused of “sophistry.” Mark Francois, a Tory Eurosceptic, said Bercow had often described himself as a “servant of this House” but “I have never known any occasion when any Speaker has overruled a motion of the House of Commons.”

“The answer is simple,” replied Bercow, who then explained, “We’re not speaking here of a motion but of an amendment to a motion. I’m sorry but there is a distinction between a motion and an amendment.”

Speaker of the House of Commons John Bercow speaks in the U.K. House of Commons in London on Jan. 9, 2019.U.K. Parliament via AFP/Getty Images

Labour MPs, and even some Tories, defended the Speaker. Ken Clarke, a former Tory cabinet minister, said Bercow was allowing the Commons to express itself.

“I would suggest to some of my honourable friends — the ones that are getting somewhat overexcited — that perhaps they should don a yellow jacket and go outside,” he said.

The amendment was passed by 308 votes to 297 — a second blow for May in as many days. On Tuesday, a cross-party group of rebels defeated the government on a finance bill. Twenty Conservative MPs, including 17 former ministers, voted for a Labour amendment that would prevent the government altering certain taxes in the event of no deal.

If May losses her “meaningful vote” on Brexit Tuesday it opens the way for the Commons to vote on alternatives, including a managed no-deal or even a second referendum. Labour said if the vote is lost, it would hold a vote of no confidence in May, which if passed would almost certainly trigger a general election.

Meanwhile, Wednesday night there was speculation that Bercow’s position might be becoming untenable with MPs plotting revenge over his decision.

Following the execution of Charles I, it was Cromwell who would become Lord Protector of England, Scotland and Ireland during the republican Commonwealth. It was also Cromwell who dismissed the so-called Rump Parliament — “You have sat too long for any good you have been doing lately” — he also had the Speaker pulled from his chair and declared the Speaker’s mace nothing but a “fool’s bauble.”